Like many things in the skincare world, sun protection can be somewhat confusing, even daunting for some. The same applies when choosing a sunscreen, but only because the world of beauty marketing has made it that way. Physical? Mineral? Chemical? What it does it all mean? And is one better or safer than the other?
Let’s start with some fundamentals…
Sunscreens are classified into two categories based on the type of UV filters they contain: organic (what we commonly refer to as “chemical”) and inorganic (“mineral” or “physical”). For the sake of simplicity and ease, we will use the words “chemical” and “mineral” because we are most familiar with these terms.
Chemical filters are categorized as organic because they contain carbon atoms, the basis of all organic matter. Examples of common U.S. chemical filters include Avobenzone, Octisalate, Oxybenzone, Homosalate and Octocrylene. It is understood that chemical sunscreens perform by absorbing and converting UV light into heat within the skin.
Mineral filters, such as Titanium Dioxide or Iron Oxide, are metal oxides that don’t contain carbon; they’re made up of metal and oxygen. Unlike their chemical counterparts, mineral filters have been understood to be physical blockers that sit on top of the skin and scatter or reflect UV light.
What’s the deal with chemical sunscreens (and are they harmful?)
Lately, chemical sunscreens have been steeped in debate – largely because “clean beauty” retailers and “clean beauty” advocates on social media continue to denigrate them as unsafe; the word “chemical” doesn’t fit neatly into the clean beauty story. Not to mention the fear-mongering around chemical sunscreens – this has been further perpetuated by studies indicating that UV filters such as Avobenzone, Oxybenzone, Octocrylene, Homosalate, Octisalate, and Octinoxate are systemically absorbed into the bloodstream.[1]
The FDA continues to review data on this matter, and study findings do NOT indicate that consumers should refrain from using these filters. These same filters are very effective in preventing sunburns, and sunburns are known to increase the risk of skin cancer.
The important thing to remember here is that all skincare ingredients, including UV filters, are “chemicals” – they have mass and take up space. But thanks to eager beaver marketers, they have created misguided classification systems, not just with sunscreens, but within the broader beauty industry. Would you buy a “clean” product with the words “inorganic sunscreen” on the label?
And contrary to popular belief – while “mineral” or “physical” sunscreens are often perceived as more “natural” – mineral UV filters may need to be processed and coated before their application in a sunscreen formulation to improve stability, dispersion, and overall performance. There is also the debate around Zinc Oxide in nanoparticle form (nano-ZnO), which is used to improve the overall user experience (i.e. less white cast) of a sunscreen, but poses a potential risk to human health and the environment.[2]
Micronized Zinc Oxide, on the other hand, is a popular choice by brands and formulators. It improves user experience and is not systemically (internally) absorbed. As a note, all SMD mineral sunscreens feature micronized Zinc Oxide and not nano Zinc Oxide.
So which sunscreen should you choose?
At the end of the day, the sunscreen you should choose is the one you will consistently use every single day. Sunscreen is a highly personal choice, so pick one you enjoy using and that feels right for you. However, here are a few key things to consider:
• Mineral sunscreens are less likely to cause a stinging sensation, irritation, or an allergic reaction, making it better for sensitive, easily-reactive skin types (like those prone to rosacea or melasma). At SMD, the most popular SPFs for sensitive skin include: Sheer Physical Sunscreen, Hydra Pro Mineral Sunscreen, and Mattifying Mineral Powder Sunscreen.
• Chemical sunscreens are more cosmetically elegant formulations than most mineral sunscreens; and work for all skin tones since they don’t leave a white cast. At SMD, the most popular chemical sunscreens include: Essential Glow Tinted Sunscreen, Essential Sheer Sunscreen, and Essential Moisturizing Sunscreen.
• Many sunscreens contain a combination of mineral and chemical UV filters, and for many, that is the “best of both worlds” as these products contain the broadest level of coverage (UVA and UVB).
Written by Maya
Reviewed by Ashley Smith, MD
[1] Murali Matta et al. 2020. ‘Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients.’ JAMA. 323 (3): 256-267.
[2] Jia Du et al. 2020. ‘ZnO Nanoparticles: Recent Advances in Ecotoxicity and Risk Assessment’ Drug Chem Toxicol. 43 (3): 322-333.